25 research outputs found
β-delayed particle decay of 9C and the A = 9, T = 1/2 nuclear system: Experiment, data, and phenomenological analysis
The β decay of 9C (T1/2 = 126.5 ms) has been studied in two experiments observing about 15 × 107 and 8 × 107 decays, respectively, at the TISOL facility at TRIUMF; different detector configurations were employed in the two experiments. In this first of two papers, the two experimental setups are described, as well as data analysis and a phenomenological approach to deducing branching ratios to and from states in 9B. In the experiments single spectra, and double and triple coincidence spectra, were recorded. Several states in 9B were observed; β-branching ratios to these states, and particle decay channels from these states, are reported. In particular, secondary decays into the 5Li and 8Be ground states were observed. With the inclusion of a considerable continuum and additional states, fair agreement with the reported 9Li logft values is found with a phenomenological approach for deducing the branching ratios. To extend the discussion, in a second, forthcoming paper, a multichannel, multistate R-matrix analysis of these data will be described
Muon capture by 3He nuclei followed by proton and deuteron production
The paper describes an experiment aimed at studying muon capture by
nuclei in pure and mixtures at various densities. Energy distributions of
protons and deuterons produced via and are measured for the
energy intervals MeV and MeV, respectively. Muon capture
rates, and are obtained using two different analysis methods. The
least--squares methods gives , . The Bayes theorem
gives ,
. The experimental
differential capture rates, and , are compared with theoretical
calculations performed using the plane--wave impulse approximation (PWIA) with
the realistic NN interaction Bonn B potential. Extrapolation to the full energy
range yields total proton and deuteron capture rates in good agreement with
former results.Comment: 17 pages, 13 figures, accepted for publication in PR
Nucleon charge exchange on the deuteron: A critical review
The existing experimental data on the d(n,p)nn and d(p,n)pp cross sections in
the forward direction are reviewed in terms of the Dean sum rule. It is shown
that the measurement of the ratio of the charge exchange on the deuteron to
that on the proton might, if taken together with other experimental data, allow
a direct construction of the np -> np scattering amplitude in the backward
direction with few ambiguities.Comment: 7 pages with 3 figure
Antimatter Regions in the Early Universe and Big Bang Nucleosynthesis
We have studied big bang nucleosynthesis in the presence of regions of
antimatter. Depending on the distance scale of the antimatter region, and thus
the epoch of their annihilation, the amount of antimatter in the early universe
is constrained by the observed abundances. Small regions, which annihilate
after weak freezeout but before nucleosynthesis, lead to a reduction in the 4He
yield, because of neutron annihilation. Large regions, which annihilate after
nucleosynthesis, lead to an increased 3He yield. Deuterium production is also
affected but not as much. The three most important production mechanisms of 3He
are 1) photodisintegration of 4He by the annihilation radiation, 2) pbar-4He
annihilation, and 3) nbar-4He annihilation by "secondary" antineutrons produced
in anti-4He annihilation. Although pbar-4He annihilation produces more 3He than
the secondary nbar-4He annihilation, the products of the latter survive later
annihilation much better, since they are distributed further away from the
annihilation zone.Comment: 15 pages, 9 figures. Minor changes to match the PRD versio